Does the anvil with the red blob on it pivot into two positions? The scaling, being red on one side implies that it refers to the measurement to the red portion of the anvil, and if the anvil doesn't pivot then the object being measured has to be an odd shape.

My first guess is that is for magnifying the measurement of something fairly thin such as sheet metal or whatever )

(When I first saw it I thought that it was a jewellers gem measure, but I think the small size of the moving 'beak' precludes that)

It is a pair of seal pliers for putting the seals on electricity meters in the UK. The flat type with the little raised bit at the end, uses bowden cable threaded through the meter screw heads, and a soft tinned copper tube crimpted on to the cable using this tool

You may well be right Andrew, but the sealing pliers being used on the gas meter and different to the more modern electric ones, which have a profile exactly the same shape as those jaws, I will try to get a picture of one tomorrow.Phil

What intrigues me is the fact that there doesn't seem to be a "1" on the scale, even in the resting position it is in appears to be a '1.5' reading. or something similar. The "V" in the upper arm makes me think it is for measuring something flat along an edge, or making sure it only hits one very small area since the whole 'arm' will swing up and change the alignment.

Still have no idea what measures start at 2 and have the aforementioned 3=7, 4=8, 5=9.

I am actually intrigued by the milling marks to either side of the reading line, as well as the fact that it looks like the scale is see-through plastic?

I have been searching the net and found two other tools with similar scales. I think as Andrew it is a Gem measure. The scale could be some other type than the two photos. Vintage Antique Germany Brass Steel Spring Gemstone Diamond Jewelers Caliper